The general aim of this project is to develop antibody-based reagents capable of altering cell-specific functions. This work utilizes cell-specific monoclonal antibodies conjugated to either toxins or recombinant retroviral gene delivery vectors. One of the approaches in this project is the development of antibody-toxin conjugates capable of eliminating specific immunological in vivo responses. The targeted cells are helper T cells expressing specific Vbeta chains in their T cell receptor. The Vbeta chain is responsible for the recognition of various Staphylococcal and Streptococcal enterotoxins, and for the development of shock syndrome arising from this interaction. We have constructed an antibody-toxin conjugate utilizing a monoclonal antibody that recognizes the Vbeta-8.1-8.2 T cell receptor. We have found that this conjugate specifically deletes T cells expressing the Vbeta-8 T cell receptor chain, resulting in a dose-dependent elimination of in vivo Vbeta-8+ T cell function and of enterotoxin-induced morbidity. The second aspect of this effort is to determine the potential for antibody-mediated retroviral infection. This laboratory's work with protein toxin conjugates has involved altering the specificity of the normally non-specific plant or bacterial toxins. The specificity has been determined by the chemically coupled antibodies or other ligands. As an extension of this laboratory's expertise in the directed cell delivery of toxins, a project concerned with cell-specific viral infection has been initiated. We will be altering the viral surface glycoprotein (gp70), where binding specificity has been demonstrated, by both chemical and molecular biological means. These chemical modification methodologies will be coincidental with those that the laboratory has developed for toxin moieties. To evaluate the efficiency of the infective process we have established highly sensitive and easily automated assays for transduced reporter gene expression in the targeted cells.